Theta Harvesting Explained: Concepts, Code Structure, and Hidden Failure Modes

A technical article by Shakti Tiwari on DEV Community breaks down theta harvesting — an options strategy focused on collecting time decay — from first principles, without citing live market data. The piece emphasizes that the strategy appears straightforward in demos but frequently breaks in production due to overlooked implementation details. Tiwari identifies three core components — observation, decision, and cost — noting that most tutorials omit the third, which covers realistic fill models, fee schedules, and tax rules. He warns that skipping proper timestamping, past-only data rules, or realized fill costs introduces look-ahead bias, data leakage, or inflated profitability. The article frames disciplined system design — not the trading idea itself — as the true differentiator between a working strategy and a flawed one.